The present invention relates to a sputtering target supporting device, and particularly to a device for securing, to a common electrode, a plurality of beams forming a mosaic target used for co-sputtering two or more kinds of metal to form a thin film.
For instance, in a co-sputtering to form a thin film of alloy MoSi.sub.2 of molybdenum Mo and silicon Si, a mosaic target comprising, in combination, molybdenum beams 1 and silicon beams 2 as shown in FIG. 1 is used. Beams 1 and 2 are fixed to an electrode 5, which also serves as a radiator or cooling plate, by having an inner holder 3 and an annular outer holder 4, shown in FIG. 2, secured to the electrode 5 by means of screws 3a and 4a, as shown in FIGS. 3 and 4.
The above-described fixing method has a disadvantage in that contact pressure between the beam and the electrode is not sufficient with respect to some of the beams because of an error in the dimensions of the beams and the holders. When the contact pressure is insufficient, the contact resistance is increased. Moreover, the electrode 5 also serves as a cooling plate as described above, so that the decreased contact pressure makes the cooling of the beam insufficient. For this reason, the temperature of the beam increases, and an electric power used for the discharge becomes insufficient. As a result, sputtering yield is decreased. The sputtering yield of some of the beams may be so much decreased that it is smaller than the rate of re-deposition of the ionized sputter atoms. Consequently, the composition of the thin film formed by sputtering varies.